From: Ankit Nautiyal <ankit.k.nauti...@intel.com>

This patch adds support to iterate over compressed output bpp as per the
fractional step, supported by DP sink.

v2:
-Avoid ending up with compressed bpp, same as pipe bpp. (Stan)

Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kand...@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 38 +++++++++++++++----------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
b/drivers/gpu/drm/i915/display/intel_dp.c
index 6e09e21909a1..d6c29006b816 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1716,15 +1716,15 @@ static bool intel_dp_dsc_supports_format(struct 
intel_dp *intel_dp,
        return drm_dp_dsc_sink_supports_format(intel_dp->dsc_dpcd, 
sink_dsc_format);
 }
 
-static bool is_bw_sufficient_for_dsc_config(u16 compressed_bpp, u32 link_clock,
+static bool is_bw_sufficient_for_dsc_config(u16 compressed_bppx16, u32 
link_clock,
                                            u32 lane_count, u32 mode_clock,
                                            enum intel_output_format 
output_format,
                                            int timeslots)
 {
        u32 available_bw, required_bw;
 
-       available_bw = (link_clock * lane_count * timeslots)  / 8;
-       required_bw = compressed_bpp * (intel_dp_mode_to_fec_clock(mode_clock));
+       available_bw = (link_clock * lane_count * timeslots * 16)  / 8;
+       required_bw = compressed_bppx16 * 
(intel_dp_mode_to_fec_clock(mode_clock));
 
        return available_bw > required_bw;
 }
@@ -1732,7 +1732,7 @@ static bool is_bw_sufficient_for_dsc_config(u16 
compressed_bpp, u32 link_clock,
 static int dsc_compute_link_config(struct intel_dp *intel_dp,
                                   struct intel_crtc_state *pipe_config,
                                   struct link_config_limits *limits,
-                                  u16 compressed_bpp,
+                                  u16 compressed_bppx16,
                                   int timeslots)
 {
        const struct drm_display_mode *adjusted_mode = 
&pipe_config->hw.adjusted_mode;
@@ -1747,8 +1747,8 @@ static int dsc_compute_link_config(struct intel_dp 
*intel_dp,
                for (lane_count = limits->min_lane_count;
                     lane_count <= limits->max_lane_count;
                     lane_count <<= 1) {
-                       if (!is_bw_sufficient_for_dsc_config(compressed_bpp, 
link_rate, lane_count,
-                                                            
adjusted_mode->clock,
+                       if (!is_bw_sufficient_for_dsc_config(compressed_bppx16, 
link_rate,
+                                                            lane_count, 
adjusted_mode->clock,
                                                             
pipe_config->output_format,
                                                             timeslots))
                                continue;
@@ -1861,7 +1861,7 @@ icl_dsc_compute_link_config(struct intel_dp *intel_dp,
                ret = dsc_compute_link_config(intel_dp,
                                              pipe_config,
                                              limits,
-                                             valid_dsc_bpp[i],
+                                             valid_dsc_bpp[i] << 4,
                                              timeslots);
                if (ret == 0) {
                        pipe_config->dsc.compressed_bpp_x16 =
@@ -1888,23 +1888,31 @@ xelpd_dsc_compute_link_config(struct intel_dp *intel_dp,
                              int pipe_bpp,
                              int timeslots)
 {
-       u16 compressed_bpp;
+       u8 bppx16_incr = drm_dp_dsc_sink_bpp_incr(intel_dp->dsc_dpcd);
+       struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+       u16 compressed_bppx16;
+       u8 bppx16_step;
        int ret;
 
+       if (DISPLAY_VER(i915) < 14 || bppx16_incr <= 1)
+               bppx16_step = 16;
+       else
+               bppx16_step = 16 / bppx16_incr;
+
        /* Compressed BPP should be less than the Input DSC bpp */
-       dsc_max_bpp = min(dsc_max_bpp, pipe_bpp - 1);
+       dsc_max_bpp = min(dsc_max_bpp << 4, (pipe_bpp << 4) - bppx16_step);
+       dsc_min_bpp = dsc_min_bpp << 4;
 
-       for (compressed_bpp = dsc_max_bpp;
-            compressed_bpp >= dsc_min_bpp;
-            compressed_bpp--) {
+       for (compressed_bppx16 = dsc_max_bpp;
+            compressed_bppx16 >= dsc_min_bpp;
+            compressed_bppx16 -= bppx16_step) {
                ret = dsc_compute_link_config(intel_dp,
                                              pipe_config,
                                              limits,
-                                             compressed_bpp,
+                                             compressed_bppx16,
                                              timeslots);
                if (ret == 0) {
-                       pipe_config->dsc.compressed_bpp_x16 =
-                               intel_fractional_bpp_to_x16(compressed_bpp);
+                       pipe_config->dsc.compressed_bpp_x16 = compressed_bppx16;
                        return 0;
                }
        }
-- 
2.25.1

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